Nontrivial topology of bulk HgSe from the study of cyclotron effective mass, electron mobility and phase shift of Shubnikov–de Haas oscillations

Abstract

In this paper, the authors report the results of an experimental study of effective mass, electron mobility and phase shift of Shubnikov-de Haas oscillations of transverse magnetoresistance in an extended electron concentration region from 8.8×10 15 cm -3 to 4.3×10 18 cm -3 in single crystals of mercury selenide. The revealed features indicate that Weyl semimetal phase may exist in HgSe at low electron density. The most significant result is the discovery of an abrupt change of Berry phase ≈ at electron concentration ≈ 2×10 18 cm -3 , which we explain in terms of a manifestation of topological Lifshitz transition in HgSe that occurs by tuning Fermi energy via doping.

Laser Pump‐Probe Fiber‐Optic Technique for Characterization of Near‐Surface Layers of Solids: Development and Application Prospects for Studying Semiconductors and Weyl Semimetals

“…As can be seen, a sharp decrease (by an order of magnitude) of (n e ) is observed at n e ≥ 10 18 cm −3 . This finding correlates well with the abrupt change in the Berry phase Φ B which is a manifestation of topological Lifshitz transition (LT) in HgSe, occurring by turning Fermi energy via doping [30] (see also the inset in Figure 5). The correlation revealed between Φ B (n e ) and (n e ) gives a compelling argument to believe that the origin of the detected I(t) anomaly is somehow related to the nontrivial topology of HgSe, which compound was assumed to belong to inversion-breaking WSMs.…”

“…In contrast to InSb, HgSe is known for the inverse band structure, wherein the gap between the highest valence band and the lowest conduction band with the total orbital moment j = 3∕2 is identically equal to zero. [28] However, recent studies [29][30][31] strongly indicate the presence in HgSe with a sufficiently low n e of the inversion-breaking Weyl semimetal (WSM) phase along with trivial gapless phase at the Γ point of the Brillouin zone. This circumstance served as an additional motivation to test the pulsed TR-FP method on HgSe.…”

“…These samples were recently studied in refs. [29][30][31], where their basic electronic parameters are presented.…”

“…The inset shows adopted from ref. [30] dependence of normalized by Berry phase Φ B on n e . Arrow denotes electron concentration n LT ≈ 2 × 10 18 cm −3 , where abrupt change in both Φ B (n e ) and (n e ) occurs.…”

Dielectric and electronic properties of three-dimensional Luttinger semimetals with a quadratic band touching

“…along with the expression n(r s ) = (3/4π) me 2 /(α * r s ) 3 for carrier density, where m is the bare band mass and * the background dielectric permittivity. We illustrate this in the case of HgSe where the observed carrier density spans over four orders of magnitude, with n ∈ [10 16 , 10 19 ] cm −3 [24]. In the low carrier regime we obtain a satisfactory fit to the experimental values of m * for a bare band mass m/m e = 0.0353 and using * = 20 [61].…”